(1) Field of the Invention
This invention relates to a variable delay line using a lumped constant type electromagnetic delay line and enjoying a superhigh-speed rising characteristic. More particularly, this invention relates to improvements in and concerning a variable delay line which combines an inductance element formed of a wound conductor and possessed of a plurality of taps with a plurality of capacitors and, therefore, enables the delay time to be varied by suitably switching the taps.
(2) Description of the Prior Art
A superhigh-speed variable delay line is easily formed for example, by using an electromagnetic delay line which has a plurality of sections formed therein by fitting a plurality of taps on an inductance element produced by winding a conductor in a plurality of turns around a bar bobbin and connecting to these taps the first electrodes of a plurality of capacitors whose other electrodes are grounded in common connection.
Specifically, this variable delay line is completed simply by forming a plurality of fixed electrodes on an insulating panel disposed along the inductance element, connecting the taps of the inductance element to these fixed electrodes, and disposing a movable contact member in such a manner that it may be moved along the row of these fixed electrodes as to be kept in pressed contact with each fixed electrode one after another.
In the variable delay line of this nature, however, there is a possibility that when the delay line is exposed to some external vibration or impact and if the fixed electrodes are flat, the movable contact held in pressed contact with one of these fixed electrodes will move and come into contact with some other fixed electrode. As the result, the delay time once selected will vary easily. When these fixed electrodes are given an increased width, the movable contact is not so readily moved from one to another of the fixed electrodes by the external vibration or impact, and the delay time once selected is not so easily varied. The increased width, however, results in an inevitable addition to the overall size of the delay line. Desired enhancement of the increment resolution of delay time is fulfilled by increasing the number of taps and that of fixed electrodes. In this case, the increased width of fixed electrodes enlarges the size of the delay line.
Further, the connection of a plurality of capacitors to the taps of the inductance element turns out to be a difficult.